Aircraft propulsion means



C. H. ZIMMERMAN AIRCRAFT PROPULSION MEANS 5 Sheets-Sheet 1 Filed July 6, 1944 INVENTOR Charles H. Zimmerman mama ATTO R NEY- Patented Get. 26 1948 Iran STATES FFI AIRCRAFT PROPULSION MEAN S CharlesH. Zimmerman, Nichols, Conn, assignor to United Aircraft. Corporation, East Hartford, Comm, a corporation ofDelaware Application July 6, 1944, Serial No. 543,632-

19 claims.

This invention relates to aircraft; propulsion and particularly to a propeller drive system for an airplane in which the driving power is supplied Another object of the invention is to provide two interconnected engine-propeller sets wherein the propellers are rotated in opposite directions and at equal speed by like rotating engines.

A further object, of the invention is. to provide a driving system of this general type having twospeed gearing between each engine andthe re-v mainder of the system, and in which change of gear ratio can be made quickly from either one to the other speed without throttlin the. engines or disconnecting them from the system.

A further object of the invention is to provide an improved multi-engine, multi-propeller driving system for a low aspect ratio, all wing air: plane; and more specifically to provide'a two-engine drive for two widely spaced propellers at the forward lateral extremities of' such an airplane in which the engines are located in the wing on opposite sides of the pilot compartment and the engine drives are directed on opposite sides of the compartment to the propellers.

A still further object of the invention is to pro- Vide means for eliminating torsional oscillation in the engine drives.

A still further object of the invention is to provide a two-propeller, two-engine drive system of this general type for a low aspect'ratio, all wing airplane in which the engine drives are directed obliquely from the engines on opposite sides of the pilot compartment toward the propellers.

Other objects are to provide an improved interconnected multiple engine-propeller driving system having a minimum of driving shafts and interconnecting gear cases; to provide differential gear mechanism for increasing the number of. working teeth in the drive gearing in the angle gear boxes; and to provide a drive system which is light in weight and safe in flight.

Other objects will be evident from the specification and claims and from the drawings which illustrate one embodiment of the invention- In the drawings, wherein similar reference characters refer to the same parts throughout the several views,

Fig. 1 is, a plan view of an all wing, low aspect ratio airplane embodying the propeller drive system of the invention, parts being broken away to facilitate illustration.

Fig. 2'is a horizontal sectional view through the transmission means of one engine showing the fluid coupling, the two-speed gearing, and the reversin gearing.

Fig. 3 is a side elevation, partly in section, of one of the propeller driving means showing the dififerential gearing and reduction gearing in the angle gear box.

Fig. 4 is a detail sectional view on line 4-- l of Fig. 2 showing the self-energizing brake and the overrunning clutch associated with the two-speed mechanism.

Fig. 5 is a sectional view on line 55 of Fig. 2. As herein shown, the invention is embodied in a low aspect ratio, all. wing airplane it having a pilot compartment l2 centrally located in, the,

forward part of the wing and two nacelles M and I5 projecting forwardly from the leading edge It at the lateral extremities of the wing. The nacelles M and if: have propeller driving means in-,

cluding angle ear boxes [8 and 2!! which enclose reduction gearingand bevel gearing for driving two propellers 22 andZflwhich are mounted for opposite rotation on usual propeller shafts projecting forwardly from the gear boxes l3 and 20. Oneof these propellers is shown at 24 in Fig. 3.

The propellers 22 and 24' are driven by two engines 2t and 23 which may be of any type suitable for aircraft propulsion, and are herein diagrammatically illustrated as identical engines of the radial cylinder, air-cooled type. As shown in Fig. 1 these engines are mounted in the wing on opposite sides of and somewhat to the rear'of compartment l2 and have their axes of rotation inclined toward the angle gear boxes !8 and 20 respectively. The engines have transmission means 32 and 3d, hereinafter more fully described, which are connected by shafting 36 and 38 with the propeller driving means in the angle gear. boxes l8 and Zil. The transmission means of. the, two engines are interconnected by a transverse driving shaft All which has suitable angle gears at its opposite ends in angle gear boxes t2 and lll car ried by the housing for transmission means 32 and 34, so that upon disconnection of either engine from the system both propellers will be driven from the other engine. The driving elements of transmission means 32 and Mare identical except that means 32 includes reversing gearing not provided in means 34 in order that like'rotating engines may be used, and conse quently transmission means 32 has been selected for detailed illustration.

Referring to Fig, 2, 46 represents a driven shaft of engine 25 and may be the engine crankshaft or an extension thereof. A sleeve coupling 48 is splined atone end to shaft 46 and at its opposite end to the hub 50 of the driving member of a fluid coupling, the overlapping ends of shaft 46 and sleeve 48 being journalled in a bearing 54 carried by a web 56 secured between the engine crankcase 58 and a generally cylindrical transmission housing Ell forming an extension thereof. The engine torque is transmitted from shaft 46 and sleeve 48 to a short coaxial shaft 63 through a parallel arrangement of fluid coupling and epicyclic gearing. In addition to the driving member 52, the fluid coupling includes a driven member 84 which has a hub 66 rotatably mounted on shaft 53 by a plurality of rollers 58. The drivin member 62 of the coupling has a cylindrical housing member Ill which carries a ring gear 12 of the epicyclic gearing, the sun gear I4 of which is formed in the hub 55 of the driven coupling member 64. The planetary gears 16 which mesh with sun gear Hi and ring gear 12 are carried by a spider I8 splined at 80 to shaft 63.

Oil is continuously supplied to the coupling through a pipe 84 from the engine oil pump (not shown) and is drained from the coupling through a plurality of peripheral ports 86 in the housing It normally covered by a ring valve 68 which extends around the periphery of the housing and is slidable between a port closing position shown in full lines in Fig. 5 and a port open position shown in dotted lines. Due to the number of these ports and the fact that oil in the coupling is discharged through them by centrifugal force, the drain ports 86have a much greater flow capacity than the supply pipe 84. The valve is manually actuated between its open and closed positions by suitable linkage extending to the pilots compartment and connected to the ring valve 88 by rods 90, one of which is shown at the bottom of the coupling in Fig. 2. One end of rod 90 is connected to a pair of inner and outer plates 9| and 92 slidable on casing 60 and connected by a stud 93 reciprocable in a slot 94 in casing 80. Stud 93 comprises the inner race of a ball bearing 95, the outer race of which is received between spaced external flanges 96 on the ring valve 88. One of the flanges 96 has a forwardly extending stud 97 fixed thereto, as by welding, which is provided with spaced annular notches 98 and 99 adapted to receive spring pressed detents IIlIl carried by casing and rotatable with ring gear 88. As shown in full and dotted lines in Fig. 5, the notches 98 and 99 correspond to the port open and port closed positions of valve 88 and in cooperation with the detents IllEI hold the valve 88 in either open or closed position as selected by the pilot.

A planetary pinion carrier, or spider, I02

splined to shaft 63 has four equally spaced, radially projecting studs I04 each carrying a bevel pinion gear I06 meshing with bevel sun gears I08 and III! rotatably mounted on shaft 63 on bearings H2 and H4 respectively. The rotation of sun gear I08 on its bearings H2 is controlled by roller clutch mechanismand brake mechanism best shown in Figs. 2 and 4. A flange IIG secured to gear Hi8 by cap screws H8 .has a rearwardly extended flange, or drum,

I20, the outer annular surface of which is acted tion (Fig. 4) causes a roller I30 to ride over cam arm I32 and lightly apply the brake by means of a toggle linkage including links I34 and I35 carried by opposite ends of the brake band, of which link I34 forms an integral part of cam arm I322. The brake band is free to rotate with the flange I20 as the latter moves in a clockwise direction (Fig. 4) to further tighten the brake band as the tail of cam arm I32 moves farther and farther under roller I30. However, this brake applying movement is limited and controlled.

To this end the brake band is supported and guided at three equally spaced points about its periphery by mechanism, one unit of which is shown in Fig. 4. One end of a hydraulic cylinder I44 is pivotally supported on a bracket M5 formed integral with a housing I46 fixed to the brake band I22 and has a piston I48 therein provided with a piston rod I50 pivotally attached to an inwardly projecting bifurcated lug I52 integral with housing 66. The brake band is urged in a counterclockwise direction by a relatively heavy compression spring I54 acting between a flange $55 at the base of the cylinder and aflange I56 at the pivoted end of piston rod I55. The piston M8 is provided with valves I51 which allow this counterclockwise rotation to take place quickly by freely venting the hydraulic fluid in the cylinder but which vent the fluid through small bleed passages I5ia in the valves whenever the brake band with its attached cylinder moves clockwise during application of the brake. The brake band is further supported in a radial direction at each of the supporting units by a compression spring I58 in housing I46 which acts between the free end of the housing and a transverse bar IBIS which is fixed to the parallel sides of an annular Ushaped guiding and supporting member I62. Member I82, which is shown in section in Fig. 2, is rotatably supported on the inner surface of casing 69 and moves with the brake band as the latter grips the flange I20 and moves clockwise (Fig. 4) to apply the brake, or moves counterclockwise under action of springs I54 upon releas- 1 ing the brake by the movement of lever I26 in a free rotation thereof in the opposite direction. A

forwardly directed flange I64 on spider '18 of the spur gear planetary lies within the flange I20 and comprises the inner member of the clutch. The outer surface of flange I64 is provided with suitable inclined cam surfaces I66 which cooperate with rollers I68 of the clutch to lock the flanges I64 and I20 together Whenever the speed of the latter equals that of flange Its in a clockwise direction of rotation.

The sun gear IIil of the bevel gear planetary has bevel gear teeth I'll} which mesh with four bevel gears H2 mounted on studs I73 of a spider I14 fixed to the housing Ell. A beve1 gear I16 having an elongated hub H8, coaxial with shaft 63, is journalled on bearings I80 in the forward end of housing and has gear teeth I8I which mesh with the four gears I72. Power is transmitted directly from gear I'It to the propeller drive means in the forward angle gear box I4 through a universal connection I82 and shaft 36 and is also transmitted to the shaft til intercom necting the engine transmission. means 32 and by bevel gear 3% in angle gear box 62 meshing with gear teeth l85 on gear We and a niversal connection i843 between gear I83 and shaft The propeller driving means for propeller 2d shown in Fig. 3, parts of the angle gear box $11-- closing the driving means also being shown. The drive shaft 38 from the engine transmission .means 3401 engine 28 terminates in a bevel gear lot which meshes with bevel gears I92 and led. The gears Q92, 1% are supported for rotation about a transverse shaft E95 carried by a housing 193 which is rigidly sup-ported in the angle gear box 28, suitable anti-friction bearings 39'! being provided in the housing for the gears. The gears 1-92, I94 mesh with a bevel gear H96 which is splined to a short shaft 198 journalled in bearings 1298 in a housing section 202 which is rigidly 'connected by webs 264 with the housing I93 and in bearings 2H5 carried in shaft 25. The shaft .lsil has a sun pinion 2% of a planetary gearing formed integral therewith which meshes with a plurality of planetary pinions 2&8 mounted on a planetary spider 2m which is splined to the propeller-shaft at'2l2. Shaft 25 is journalled in bearings 2M carried by a housing section 2H3 which is bolted by through bolts M3 to housing section 292, a ring gear 22%! being secured between the bolted peripheries of said housings. Housing 2 it also carries a radially extended flange 222 the periphery of which is connected by bolts 224 to inwardly directed flanges 226 of the gear box 20.

It will ,be understood that oil is continuously circulated through both the housings iii] of transmission means 32 and and the angle gear boxes i8 andZil in a normal manner.

In the normal operation ofthepropellerdrive system, when both engines are transmitting their normal torque to the system, the ports .86 around the-periphery of the fluid couplings are closed by the ring valves 88 and the couplings are consequently full of oil. Under these conditions the driving and driven coup-lingmembers 62 and rotate substantially in unison. Member 64 rotates more slowly by onepercent to three percent sincethere must be some slippage in ;the fiuid coupling in order for it to transmit torque; and

.sun gear l4, ring gear '52 and planetary pinions 16 rotate as a unit to drive the spider l8 atengine speed and in the same direction as the engine driven shaft 66.

The spider 182 of the bevel planetarygearing being keyed to the shaft iat causes the planetary gears 188 to be rotated bodily at engine speed about shaft Thespeed at whichthese gears I iliiare driven about their own axes depends upon the speed of rotation of the sun gear I08 which may beflxed by the application of thebrake band [22 to. the drum, or may rotate at engine speed in the same direction as shaft 53 if this-brake band is released. Here it will be notedthatthe forwardly directed flange I64 on spider 1,8 is rotating with shaft 33 and that, while gear 108 would normally be driven in the samedirection .at a speed faster than. engine speed, itis restrained by rollers H8 of the clutch acting against inclined surfaces H55 from exceeding; the engine speed of flange Hid. Thus with the brake released the sun gear I ill, with the gear ratio shown, is driven, at engine speed by planetary gears lfili;

while with the brake applied and gear I08 stationary, sun gear Hi3 will be driven at twi-ceengine speed.

;It-,.willg;be, evident, that .with-thashait .45 driven the direction of the arrow in Fig.- 2, themepelle .22 will be driven in the opposite direction of rotation due to the reversal of drive in the bevel gears H2 pro gided in the transmissionv by the bevel gears 184 at the opposite ends, of-

the interconnecting shaft All. The system thus provides for the Opposite rotation of propellers .22, 24 by like rotating engines witha minimum of se n an aw ei It will beunderstood that when the airplane is takin eff and he ce? :is tannins at w-speed i is desirable to drive the propeller at a high H. P. M., referredto .herein as the low-airplane speedgear ratio ;-i. e,, with the brake engaged. When the planehas reached its normal cruising speed it is then desirablethatthe propellershould be driven at a lowerR. P. M. relative-to engine R. P. herein referredto as the high airplane speed gear ratio .i. e., with the bralsereleased.

To-eilect locking of gear .lfiB-by the bl'jakit is only neeessaryfor the pilot to move his controls to cause levers 25, associated with the two transmissionmeans 3 2 and 3.4,to be moved from the full to ,the dottedlineposition in Fig. 4. This movement causes an initial application of the brake band to flange lili] which causes the brake band [22, guiding member L62 and hydraulic cylinders ld l to move in a cloclgwise direction indicated by the arrow in Fig. 4, to further apply the brahe as cam arm i3 slowly moves to theright under roller l til. This slow applicationof the brake results ,frem-the slow escape of fluid through the bleed holes ifila in valves l5"! in the pistons hi8.

The brak e;oan be manually released to change .the driving gear-ratio-by a reverse movement of lever 526 into the full line position shownin Fig. 4. Themovementoi the brake in its releasing movement under the action of springs 15!: is

rapid the unseatingofvalves i5? permitting-the fluid to-pass freely .through the piston as {the yi nd d rnove countercl ck i mauve .the pistons.

t6. Due to centrifugalforoe aeting on the oil,

the coupling will drain through the ports; 86 more rapidly than oil can be supplied through pipe 184 and the driven clutch member :64 will no longer be driven by clutch member. 8 2. As the ring valves 3.8 of the tr ansmissionmeans 32, 34 are separately operable, either engine or both engines can be disconnectedfrom the drive system. Assuming that the, engin e.26 of the transmission means32 is disconnected at its fluid coupling and the other engine 28 continues todrive the system, it will be evident that the gear l08'a'nd the drum I20 will slow up, stop, and finally rotate in a reversedirection. The roller clutch under these conditions will permit flange i281 to rotate freely in this reversedirection while the drive from engine 28 ar d vin he i t nc neesie rrqrdetainee .a

previously described, gears I08 and the connected drums I will be rotating in the direction of engine rotation, i. e. clockwise as viewed in Fig. 4, at a speed not exceeding the speed of rotation of the engine shafts. If engine 26, for example, should fail under the above conditions, gear 18 and attached drum I20 of its transmission would no longer be driven in the direction of engine rotation by shaft 63 but instead would be driven in the reverse direction (counter-clockwise Fig. i by pinions I08 as the latter are rotated about their own axes by the drive from engine 28. This reverse rotation is permitted by the roller clutch just as in the case of the manual diconnection at the fluid coupling previously discussed. It will be noted that with the above described transmission system whatever torque the engine 26 may develop, even though it may be developing only partial torque, will be utilized in driving the interconnected propeller system.

Should engine 26 fail when the brake is on, the reverse rotation of drum I20 will cause the brake to be released automatically into the dotted position of lever I26 and roller I30, shown in Fig. 4, enabling the other engine 281 to drive both propellers independently of the defective engine.

As a result of these improvements it will be evident that a drive system has been provided for driving two oppositely rotating propellers from two like rotating engines, in which either engine or both can be disconnected from the system by the pilot and in which either engine is immediately disconnected from the driving system automatically upon its failure to produce sumcient torque to supply power to the system. Further, there has been provided in such a system improved two-speed gearing between each engine and the system in which change of gears can be made from one to the other gear ratio without throttling the engines or disconnecting them from the system. Also as a result of the fluid couplings included in-the engine drives, it will be evident that torsional oscillations in the engines will not be transmitted to the interconnected propeller system. 1

It will be further evident that a drive system of the above type has been provided which is especially adapted for a low aspect ratio, all wing airplane wherein propellers located at the forward lateral extremity of such an airplane are driven by engines located in the wing by drive mechanism extending on opposite sides of the centrally located pilot compartment.

It will further be evident that, as a result of the improved drive system in which the engine drives are directed obliquely from the engines located on opposite sides of the pilot compartment toward the propellers, an improved and simplified driving system has been provided requiring a minimum of gearing and shafting.

While only one embodiment of the invention has been shown and described herein, for purposes of illustration, it is to be understood that various changes in the construction and arrangement of the parts may be made without departing from the scope of the following claims:

I claim:

1. In an aircraft, a streamlined body having two laterally spaced propellers including propeller shafts mounted for opposite rotation at the lead ing edge thereof, a pilot compartment within said body between said propellers, two like rotating engines mounted within said body having driving shafts on opposite sides of said compartment, power transmission means connecting the shafts g of said engines respectively with the shafts of said propeliers including two-speed mechanism, means for interconnecting said transmission means including a transverse shaft capable of transmitting the power from either engine to the 'ransmission means associated with the other engine, means for reversing the drive of one of said engines in one of said engine transmission means, and means operative upon reversal of torque in the driving shaft of either engine for disconnecting that engine from its transmission means.

2. In an all-wing low aspect ratio aircraft, an airfoil having two widely spaced propellers mounted for rotation at the forward edge thereof e and including parallel propeller shafts having reduction gearing at their inboard ends, a pilot compartment in said airfoil between said propellers, two engines mounted in said airfoil between said propellers and disposed toward the rear of said compartment having axial drive shafts located between and disposed at oblique angles relative to said propeller shafts, transmission means directly connecting said drive shafts respectively with the reduction gearing of said propellers including shafting aligned with said engine drive shafts, and means interconnecting said transmission means including a transverse shaft capable of transmitting the power from either engine to the transmission means associated with the other engine.

3. An all-wing low aspect ratio airplane having laterally spaced propeller nacelles projecting forwardly from the leading edge thereof at opposite lateral extremities, oppositely rotating propellers mounted on said nacelles having their remote blades moving downwardly propeller driving means in each nacelle including a propeller shaft and a reduction gearing, a pilot compartment in said Wing between said nacelles, two like rotating engines mounted within said Wing between said nacelles having driving shafts, trans mission means connecting said engines respectively with the reduction gearing in said nacelles one of said transmission means having means for reversing the drive of its associated engine, means interconnecting said transmission means including a transverse shaft capable of transmitting the power from either engine to the transmission means associated with the other engine, and means operative upon reversal of torque in the driving shaft of either engine for disconnecting that engine from its transmission means.

4. An all-wing low aspect ratio airplane having laterally spaced nacelles projecting forwardly from the leading edge adjacent the lateral extremities thereof, propeller driving means in each nacelle including a fore and aft extended propeller shaft and a reduction gearing, a pilot compartment in said wing between said nacelles, two engines mounted adjacent each other in said wing on opposite sides of the fore and aft centerline of said wing between the axes of said propeller shafts with their axes of rotation directed forward and outwardly toward the respective reduction gearing of said propellers, transmission means directly connecting said engines with said gearing extending obliquely with respect to said propeller shafts on opposite sides of said compartment, and means interconnecting said transmission means including a shaft capable of transmitting the power from either engine to the transmission means associated with the other engine.

5. In a multiple engined aircraft, a plurality of engine-propeller sets, each set including a propeller having a shaft, an engine having a shaft and drive means connecting said eng'ine' and propeller shafts, means for interconnecting the drive means of the sets, whereby all the propellers can be driven by the engine of any set, the drive in of each set having two-speed mechanism including clutch means operated upon reversal of torque in the engine shaft for automatically disconnecting the engine from the system, and means between the engine and said two-speed mechanism for absorbing torsional cscillations originating in the engine shaft.

6. In a two engined aircraft, two engine-propeller sets, each including a propeller having a shaft, an engine having a shaft and drive means connecting shafts, means interconnecting the drive means of the sets, whereby both propellers can be driven from either engine, each drive means having a fluid coupling including driving and driven members, planetary gearing having a sun gear connected to one of said members, a ring gear connected to the other of said members and a planet pinion carrying member having pinions meshing with said sun and ring gears, means for supplying fluid to said coupling, and'me'ans for draining the fluid from said coupling.

7. In a two engined aircraft, two engine-propeller sets, each including a propeller having a shaft, an engine having a shaft and drive means connecting said shafts, each drive means having an engine driven shaft and a fluid coupling con necting the latter shaft with the engine shaft including driving and driven. coupling members, planetary gearing having a sun gear connected to one of said members, a ring gear connected to the other of said members and a planet pinion carrying member fixed to said engine driven shaft having pinions meshing with said sun and ring gears, means for constantly supplying fluid to said coupling, and means having a greater flow capacity than said fluid supplying means for draining the fluid from said coupling for disconnecting the drive between said engine shaft and said engine driven shaft.

8. In a two engined aircraft, a drive system comprising two engine-propeller sets, each including a propeller having a shaft, an engine having a shaft and drive means connecting said shafts, and means for interconnecting the drive means of the sets, each of said drive means having means for automatically disconnect ng each engine from the drive system upon failure of that engine, whereby both propellers are driven from the other engine, said last mentioned means including an intermediate shaft, a spider carrying planetary pinions rotatable with said intermediate shaft. two sun gears rotatably mounted on shaft and meshing with said planetary pinions, one of said sun gears being operatively connected with the drive system, and means including a roller clutch having one clutch element thereof connected to said shaft and the other clutch element thereof connected to said other sun gear for permitting said other sun gear to rotate freelv in a direction reverse to the direction of rotation of said shaft While limiting the speed of rotat on in the other direction to the speed of rotation of said shaft.

9. In a twoengined aircraft, two engine-p-ropeller sets, each including a propeller having a shaft, an engine having a shaft and drive means connecting said shafts. means interconnecting the drive means of the sets, whereby both propellers can be driven from either engine, the drive means of each set including a shaft driven from the engine shaft, meansforming a disconnectible con nection between said last mentioned shafts including a fluid coupling and a planetary gearing connected in parallel, said coupling having a driving member connected with said engine shaft and a freely rotatable driven member, and said planetary having a ring gear carried by said driving member and a sun gear carried by said driven member, and a spider fixed to said engine driven shaft having planet gears meshing with said sun and ring gears. Y

10. In a two engined aircraft, two engine-propeller sets, each including a propeller driving shaft, an engine driven shaft and drive means connecting said shafts, means for interconnecting said drive means of the sets, each of said drive means including an overrunning clutch having one member driven by the engine driven shaft, another clutch member rotatable thereoma twospeed mechanism including a sun gear carried by said other clutch member, and a planet gear carrying member fixed to said engine driven shaft having planet pinions meshing with said sun ear, and a second sun'gear meshing with said planet gears and connected with said drive means, and releasable means for holding said other clutch member.

11. In a two engined aircraft, two engine-progine driven shaft comprising a fluid coupling including driving and driven members, planetary gearing having a sun gear connected to one of said members, a ring gear connected to the other of said members and a planet pinion carrying member fixed to said engine driven shaft having pinions meshing with said sun and ring gears, means for supplying fluid to said coupling, means for draining the fluid from said coupling, means for automatically disconnecting said engine from its drive means upon reversal of torque including an overrunning clutch having one member flxed to said engine driven shaft and another member connected to said interconnected drive means. i

12. In a multiple motored aircraft, a plurality of engine-propeller sets, saidsets including a propeller having a shaft and an engine having a shaft and drive means connecting said shaftsincluding an engine driven shaft, means including a transverse shaft for operatively connecting said drive means of said sets, and means on the engine side of said transverse shaft operative upon reversal of torque of either motor for permitting the other motor to drive the propellers of both sets independent of the defective motor, said last mentioned means comprising two-speed mechanism including an overrunning clutch having one clutch member fixed to said engine driven shaft, a second clutch member rotatable on said shaft,

a planet pinion carrying member fixed to said of engine-propeller sets, each of said sets including a propeller having a shaft, .an engine having a shaft and drive means connecting said shafts including an engine driven shaft, means including a transverse shaft for operatively connecting said drive means of said sets, and means on the engine side of said transverse shaft operative upon reversal of torque of either motor for permittin the other motor to drive the propellers of both sets independent of the defective motor, said last mentioned means comprising two-speed mechanism including an overrunning clutch having one clutch member fixed to said engine driven shaft, a second clutch member rotatable on said shaft, a planet pinion carrying member fixed to said engine driven shaft having planet pinions thereon, two sun gears rotatable on said shaft, one operatively connected to said drive means and the other fixed to said other clutch member, brake means for holding said other clutch member, and means for releasing said brake upon failure of the connected engine.

14. In an aircraft, a plurality of engines, a plurality of propellers, means for interconnecting said propellers whereby all the propellers may be driven by any engine, and transmission means for connecting each engine to the interconnected propeller system and for automatically disconnecting the engine upon failure including a planetary gearing comprising a p nion carrier driven by the engine having a plurality of planetary pinions thereon meshing with two gears of the planetary gearing, one of said gears being driv ngly connected to the propeller system and the other being rotatably mounted, means for effecting rotation of both of said gears w th said carrier at engine speed, and means for holding sa d rotatable gear to effect rotat on of said planetary pinions about their respective axes.

15. In an aircraft, a plurality of engines, a plurality of propellers. means for interconnecting sa d propellers whereby all the propellers may be driven by any engine, and transmission means for connecting each engine to the interconnected propeller system and for automatically disconnecting the engine upon failure including a planetary gearing comprising a pinion carrier driven by the engine having a plurality of planetary pinions thereon meshing with two gears of the planetary gearing, one of sa d gears being drivingly connected to the propeller system and the other being rotatably mounted, means for effecting rotat on of both of said gears with said carrier to drive said propeller system at one speed ratio, means for holding said rotatable gear to cause rotation of said planetary pinions about their respective axes and drive said propeller system at another speed ratio, and means automatically operative upon failure of the engine for releasing said holding means.

16. In an aircraft, a plurality of engines, a plurality of propellers, means for interconnecting said propellers whereby all the propellers may be driven by any engine. and transmission means for connecting each engine to the interconnected propeller system including a two-speed mechanism having means for automatically disconnecting the engine upon failure including a planetary gearing comprising a pinioncarrier driven by the engine having a plurality of planetary pinions thereon meshing with two gears of the planetary gearing, one of said gears being drivingly connected to the propeller system and the other being rotatably mounted adjacent an engine driven member, means for effecting bodily rotation of both of said gears and said carrier with said member to provide one speed ratio including means for restraining said rotatable gear from rotating faster than said member, and releasable means for holding said rotatable gear to effect rotation of said planetary pinions about their respective axes to provide the second speed ratio.

17. In an aircraft, a plurality of engines, a plurality of propellers, means for interconnecting said propellers whereby all the propellers may be driven by any engine, and transmission means for connecting each engine to the interconnected propeller system including a fluid coupling and a twospeed mechanism having means for automatically disconnecting the engine upon failure including a planetary gearing comprising a pinion carrier driven by the engine having a plurality of planetary pinions thereon meshing with two gears of the planetary gearing, one of said gears being drivingly connected to the propeller system and the other being rotatably mounted adjacent an engine driven member, means for effecting bodily rotation of both of said gears and said carrier with said member to provide one speed ratio including means on said engine driven member for restraining said rotatable gear from rotating in the same direction faster than said member, releasable means for holding said rotatable gear to effect rotation of said planetary pinions about their respective axes to provide the second speed ratio, and means controlled by the pilot for disconnecting the engine at said fluid coupling.

18. In an aircraft, a plurality of engines, a plurality of propellers, means for interconnecting said propellers whereby all the propellers may be driven by any engine, and transmission means for connecting each engine to the interconnected propeller system and for automatically disconnecting the engine upon failure including a planetary gearing comprising a pinion carrier driven by the engine having a plurality of planetary pinions thereon meshing with two gears in the planetary gearing, one of said gears being drivingly connected to the propeller system and the other being rotatably mounted adjacent an engine driven member, means for effecting bodily rotation of both of said gears and said carrier at the speed of said member including an overrunning clutch connection between said member and said rotatable gear for restraining said rotatable gear from rotating faster than said member in the same direction of rotation while permitting free rotation relative thereto in the opposite direction, and releasable means for holding said rotatable gear to effect rotation of said planetary pinions about their respective axes to drive said propeller system at a speed other than the speed of said member.

19. In an aircraft, a plurality of engines, a plurality of propellers, means for interconnecting said propellers whereby all the propellers may be driven by any engine, and transmission means for connecting each engine to the interconnected propeller system and for automatically disconnecting the engine upon failure including a shaft driven by the engine carrying a planetary pinion carrier and a plurality of planetary pinions thereon meshing with two gears of a planetary gearing, one of said gears being drivingly connected to the propeller system and the other being rotatably mounted on said shaft, a clutch member rotatable with said rotatable gear, a second clutch member rotatable with said shaft, cooperating clutch elements between said members permitting rotation of said rotatable gear freely in one direction while restraining its rotation in the direction of rotation of said shaft to the speed of said 13 shaft, and releasable means for holding said ro- Number tatable gear against rotation. 1,421,803 CHARLES H. ZIMMERMANr 1,431,244 2,059,122 REFERENCES CITED 5 2 120 321 The following references are of record in the file of this patent:

Number UNITED STATES PATENTS 533 047 Number Name Date 1 0 452,922

1,089,029 Zimmerman Mar. 3, 1914 Name Date Martin July 4, 1922 Mandel Oct. 10, 1922 Lansing Oct. 27, 1936 Waseige June 14, 1938 FOREIGN PATENTS Country Date Great Britain July 17, 1941 Great Britain Sept. 1, 1936 

